Interesting, since git is used by kernel devs this can't just be a convenience thing. Why are they so adamant about putting the patch in the email?
git format-patch, git send-email as well as git am work also really well and simplify the patch creation/integration. This is basically the send a pull request from github but without the need to depend on github.
Task assigned to developer via email, developer takes current release tar from ftp and untars, does work, creates patch, forwards patch to colleague to review, forwards to release manager who integrates all incoming patches, drops into a new tar, releases to ftp.
Some of this was automated with a few hundred lines of perl. The rest was on a whiteboard.
They could skip the ftp part, because git saves bandwidth
Still, this is a good way to do the work
Unit tests are great in js/python/ruby because of the nature of the language
In C/C++ for example it's much more involved. In java it's bearable because of Eclipse/Netbeans facilitating lots of things.
But take for example the Linux kernel development: - There are two widely used "IDEs": VIM and Emacs, pick one
- Patches sent over email (yeah, please try doing a pull request to see what happens)
- No unit tests
- limited use of debuging tools, mostly printk
And still is one of the most solid and used softwares out there
Tools and techniques (unit tests, CI, etc) are good if you want to have several developers "with their hands on the code at the same time" and you have limited trust on them